The amount that qualifies as chump change varies according to the situation: for instance, in the context of the October 1, 2017—September 30, 2018 U.S. military budget of $824.6 billion, an expenditure of (say) $1.3 million could be regarded as chump change.

A discussion on the website of the Word Detective, Evan Morris, explains how the term probably came into being, and casts light on a few other words along the way that sound similar.